The present disclosure relates to a sheet feed device used to stock beforehand a multitude of sheets, such as paper sheets, to be supplied to an image forming apparatus and to feed the sheets thus stocked one by one, and the image forming apparatus incorporating the sheet feed device.
In an image forming apparatus represented by a copy machine or a printer, a paper feed cassette is used for feeding paper such as cut paper. The paper feed cassette is stocked beforehand with a multitude of paper sheets before printing and supplies, from an uppermost layer of a stack of the paper sheets stacked in the cassette, the paper sheets one by one separately from each other.
The paper feed cassette is provided with a sheet stacking plate having an upper surface on which paper sheets are placed. The paper sheets are stacked on the sheet stacking plate that is biased upward, and at a cassette mounting position in the image forming apparatus, a pickup roller provided on an image forming apparatus main body side comes in contact with an upper surface of an uppermost one of the paper sheets. Then, the pickup roller turns, causing the paper sheets to be fed out in order in a feed direction by a frictional force between the pickup roller and the uppermost one of the paper sheets.
By the way, in a paper feed device in which a paper feed cassette is disposed such that an insertion/pull-out direction thereof is orthogonal to a feed direction of a paper sheet, in a case where, when the paper feed cassette is inserted/pulled out for the purpose of paper sheet replenishment or the like, paper sheets stacked therein come in contact with a pickup roller while the insertion/pulling out of the paper feed cassette is in progress or have been in contact therewith prior to the insertion/pulling out of the paper feed cassette, the contact with the pickup roller causes an uppermost one of the paper sheets to be misaligned in the cassette insertion/pull-out direction, resulting in a problem that a paper sheet is fed out in an obliquely oriented state. Moreover, problems such as causing a paper sheet to be flawed or torn or causing a paper sheet to fall off from the paper feed cassette also are likely to occur. Also, the contact between the pickup roller and the paper sheets interferes with the insertion/pulling out of the cassette. In addition, there may occur sagging of a paper sheet between a width alignment cursor that regulates a paper sheet position in the direction orthogonal to the feed direction and the pickup roller, resulting in bending of the paper sheet at its end portion or a paper jam.
As a measure to solve these problems, there is known, for example, a paper feed, device including a pickup roller support body that supports a pickup roller to an apparatus main body such that the pickup roller is swingable in such a direction as to approach/separate from an upper surface of a paper sheet and a swing control body that is mounted to the apparatus main body such that it is movable substantially integrally with a cassette in accordance with insertion/pulling out of the cassette and controls a swing position of the pickup roller support body (position to which the pickup roller support body is swung). In the paper feed device, in accordance with insertion/pulling out of the cassette, the pickup roller is made to swing to be positioned as follows. That is, at the time of inserting the cassette, as the cassette approaches a mounting position of the cassette, the pickup roller swings to be positioned so as to increasingly come into contact with an upper surface of a paper sheet, and at the time of pulling out the cassette, as the cassette separates from the mounting position, the pickup roller swings to be positioned so as to increasingly separate from the upper surface of the paper sheet.